How to use xft font in unicode-xft branch

[Leon]

Hi there,

Just compiled unicode-xft and it works. I don't know how to use xft
fonts. And it seems no document at all about the xft branch. For
example, emacs -fn "mono" will give

,----[ emacs -fn mono ]
| Font `mono' is not defined
`----

Any idea how to test if emacs has xft support??

-- 
Leon
GNU Emacs 23.0.0.1 (i686-pc-linux-gnu, GTK+ Version 2.8.17) of
2006-05-15